A Wire Bonder is a machine with which semiconductor chips are wired after mounting on a substrate. The Wire Bonder has a capillary that is clamped to the tip of a horn. The capillary serves to secure the wire to a connection point on the semiconductor chip and to a connection point on the substrate as well as to guide the wire between the two connection points. On producing the wire connection between the connection point on the semiconductor chip and the connection point on the substrate, the end of the wire protruding out of the capillary is first melted into a ball. Afterwards, the wire ball is secured to the connection point on the semiconductor chip by means of pressure and ultrasonics. In doing so, ultrasonics is applied to the horn from an ultrasonic transducer. This process is called ball bonding. The wire is then pulled through to the required length, formed into a wire loop and welded to the connection point on the substrate. This last part of the process is called wedge bonding. After securing the wire to the connection point on the substrate, the wire is torn off and the next bonding cycle can begin.
Most of the Wire Bonders available on the market today move the bondhead in the horizontal xy plane by means of two orthogonally arranged drives. An example of such a drive system is disclosed for example in the patent specification U.S. Pat. No. 5,114,302. In addition, this drive system uses vacuum pre-charged air bearings. A significant disadvantage of this known Wire Bonder exists in that on moving the bondhead to a new position, relatively large masses have to be accelerated. This requires powerful drive systems and robust bearings. A further disadvantage exists in that, depending on the position of the bondhead, on accelerating the bondhead relatively large torques occur that place great demands on the bearing of the bondhead. This puts limitations on the maximum possible acceleration values and therefore on the throughput of the Wire Bonder.
A Wire Bonder with which the movement of the bondhead takes place with a polar drive system is known from the patent specification U.S. Pat. No. 5,330,089. With this drive system relatively large masses also have to be accelerated. In addition, the load to be accelerated by the turning motion of the motor is dependent on the position of the load in relation to the linear axis which, on the one hand impedes the regulation of the movement of the bondhead and, on the other hand puts limitations on the maximum possible acceleration values.
A Wire Bonder with which the movement of the bondhead takes place with a rotary drive system is known from the patent specification U.S. Pat. No. 6,460,751. This drive system has a linear axis that has to accelerate a relatively large mass and a rotary axis that has to accelerate a relatively small mass.